js实现滚动条滚动到某个位置便自动定位某个tr_javascript技巧

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要实现带滚动条的table,定位到某个tr,其实是很简单的,只有几行js代码就可以完成,具体内容如下

js代码

<strong><script type="text/javascript"> 
 function  test(){ 
    var $objTr = $("#location"); //找到要定位的地方  tr 
    $objTr.css("background-color","lightgray"); //设置要定位地方的css 
    var objTr = $objTr[0]; //转化为dom对象 
    $("#dataDiv").animate({scrollTop:objTr.offsetTop},"slow"); //定位tr 
  } 
</script></strong>

html

<body> 
    <h1>定位</h1> 
    <p id="dataDiv" style="overflow-x:hidden;overflow-y:auto;height:400px;width:450px;"> 
      <table id="tableId" style="width:400px;background-color:yellow" align="center" border="0"> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr <span style="color:#FF0000;">id="location"</span>><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
        <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
      </table> 
  </p> 
  <input type="button" value="定位到一行" onclick="test()"/> 
 </body>

虽说是几行代码,但要彻底弄懂。要熟悉animate的使用,scrollTop,.offsetTop的意思方可得心应手。

1. animate的使用说明:

animate() 方法执行 CSS 属性集的自定义动画。

该方法通过CSS样式将元素从一个状态改变为另一个状态。CSS属性值是逐渐改变的,这样就可以创建动画效果。
只有数字值可创建动画(比如 "margin:30px")。字符串值无法创建动画(比如 "background-color:red")。

2. scrollTop

scrollTop属性

有些情况下,“元素中内容”的高度会超过“元素本身”的高度, scrollTop指的是“元素中的内容”超出“元素上边界”的那部分的高度。

解释:
内层元素的高度值300px > 外层元素的高度值200px,因此“外层元素的内容”(也就是“内层元素”)无法完全显示,而外层元素把overflow设置为auto,因此外层元素的右侧会出现竖直滑动条
初始状态下,“内层元素的上边界”和“外层元素的上边界”重合,没有任何内容超过“外层元素的上边界”,此时scrollTop属性的值为0。

当向下拖动滚动块时,超过“外层元素的上边界”的内容会逐渐增多,scrollTop值就等于这些超出部分的高度。
当拖动滚动块到最底部时,“内层元素的下边界”和“外层元素的下边界”重合,此时,超过“外层元素的上边界”的内容的高度=300px-200px=100px,也就是此时的scrollTop值。

3..offsetTop,offsetLeft等

假设 obj 为某个 HTML 控件。

obj.offsetTop 指 obj 距离上方或上层控件的位置,整型,单位像素。

obj.offsetLeft 指 obj 距离左方或上层控件的位置,整型,单位像素。

obj.offsetWidth 指 obj 控件自身的宽度,整型,单位像素。

obj.offsetHeight 指 obj 控件自身的高度,整型,单位像素。

offsetParent

offsetParent属性返回一个对象的引用,这个对象是距离调用offsetParent的元素最近的(在包含层次中最靠近的),并且是已进行过CSS定位的容器元素。 如果这个容器元素未进行CSS定位,则offsetParent属性的取值为根元素(在标准兼容模式下为html元素;在怪异呈现模式下为body元素)的引用。当容器元素的style.display 被设置为 "none"时(译注:IE和Opera除外),offsetParent属性 返回null。

句法:parentObj = element.offsetParent

变量:parentObj 是一个元素的引用,当前元素的偏移量在其中计算。

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原文地址:http://www.php.cn/js-tutorial-2854.html

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